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Institut für Chemie
Reactor design- A Primer
Reinhard Schomäcker
Dept. of Chemistry
TU Berlin
- A selection of reactors
- Kinetic studies
- Up-Scaling of a reactor
- Simulation of a PFTR
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How to select a reactor for an industrial scale synthesis ?
“Something went wrong when we scaled-up the recipe”
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L
G
G
L
Packed Bubble Column
Tray collumn
Gas-Liquid-Reactors Fixed Bed Reactors Three Phase Reactors
Single Bed Reactor
Katalysator
GL
L G
G
Trickle Bed Reactor
G
Multi Tube Reactor
GK+L
K+L
Tank Reactor
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Select the reactor from selectivity discussion
1) More suitable chemistry (different reactants)2) Better Catalyst or reaction medium3) Better temperature4) Reaction engineering
( Type of reactor, mode of operation).
Parallel reactionsExample 1:
A + B CA + B D
BAcckr
11=
BAcckr
22=
21
1
21
1
kk
k
rr
r
Aconsumed
CproducedS
C +=
+==
S
X
A
C
D
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BAcckr
11=
r k cA2 22=
Sgebil es C
umgesetztes Ar
r r k ck c
CA
B
= =+
=+
det 1
1 2 2
1
21
1 2
A + B C2 A D
Example 2:
Example 3: consecutive reaction
A + B C
C + B D
r k c cA B1 1=
r k c cC B2 2=
A
C
C ck
ck
r
r
r
rr
Aconsumed
CproducedS
1
2
1
2
1
21 11 −=−=−==
S
X
A B C
∫=CA
CAAC
dCSS0
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z
cA
0 Lz
qnA
.
M
CSTR
cAV
0
•
cAV•
.
V
V R=τVR
Coordinate z
Zulauf Ablauf
cA
PFTR
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Kinetics of steam reforming of methanol at diff. temperatures230°C
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 0.2 0.4 0.6 0.8 1Verweilzeit [s]
Par
tiald
ruck
[atm
]
250°C
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 0.1 0.2 0.3 0.4 0.5 0.6
Verweilzeit [s]
Par
tiald
ruck
[atm
]
300°C
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 0.1 0.2 0.3 0.4 0.5 0.6
Verweilzeit [s]
Par
tiald
ruck
[atm
]
MeOHH2OCOCO2
H2
Simulation
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Reaktion mechanism from literature
CH3OH CO + 2H2CO + H2O H2 + CO2
2 CH3OH 2 HCHO + 2 H2HCHO + HCHO HCOOCH3HCOOCH3 CO + CH3OHCO + H2O CO2 + H2
2 CH3OH HOOCH3 + 2 H2HCOOCH3 + H2O HCOOH + CH3OHHCOOH CO2 + H2
B.A. Peppley, J.C. Amplett
Su, Rei, Kobayashi, Idem, Bakhshi
Takahashi, Takezawa
1.
2.3.
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Reaktion network and kinetic parameter
Ea1h= 70 kJ/mol k01h= 2,1 1012 Pa0,4/sEa1r= 120 kJ/mol k01r= 7,7 1015 Pa-3/s Ea2h= 88 kJ/mol k02h= 1,3 1013 Pa-1/s Ea2r= 47 kJ/mol k02r= 2,0 1011 Pa-1/s
m= 0,3 n= 0,3
r1h= k1h PmMeOHPn
H2O
r2h= k2h PCO2 PH2
k1h
k2h
k2r
k1r
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Pore diffusion and reaction in porous catalyst
φ = L k Ci
n-1
D
k > D k < D
particleCatalyst
ofLength ticCharakteri :L
orderReaction :n
iComponent ofion Concentrat :Ci
tcoefficienDiffusion :D
constant rate :k
Modul Thiele :φ
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Determination of reactor size
Rdz
dCu
dtdC AA −−=
∫ −=
A
A
C
C
A
RdC
0
τ
)1(0
XCCAA
−=
Material balance
dXCdCAA 0
−= ∫Φ=
eXAO
X
dX
RC
00 )(τ
)(0
XRR Φ=
Reaction time
Introduction of Conversion 0
0
A
AA
C
CCX
−=
Rd
dCA −=τ
VR
jA
RPFTR
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.
V
Vt R== τ
∫Φ=
eXAO
X
dX
RC
00 )(τ
∫Φ=
eXAO
R X
dX
R
CVV
00
.
)(
∫Φ=
eX
AO
X
dX
R
C0
0)(
τ
Calculation of Reactor Volume (PFTR)
Time required to reach conversion X
Residence time
Reactor Volume
nP=V CAo X.
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)()( XeDadz
dX XRT
E
Φ=−
∞τ
Heat removal from PFTR:
)()(K
RT
E
adTTStXeDaT
dz
dT −−Φ∆=−
∞τ
pR
WW
p
WW
cV
Fk
cV
FkSt
ρτ
ρ==
&
)(
)(0
pA
A
ad c
cHT
ρν−∆−=∆
0
0)(
Ac
kDa
τυ−=∞
0AC
R
dz
dX=τ
Zeit
Tem
pera
tur
adiabatischer Reaktor
gekühlter Reaktor
TT
aK
z
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Catalysis and mass transport in pores
reactants
activemembrane
fixed bed reactor
reactants
product
A + B C D
A + B
C
pelletproducts
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Preparation and characterisation
MOCVD 27MOCVD 27--capillary bundlecapillary bundle
• Pores- ∅: 1,9 µm
•MOCVD: about 89 mg Pd
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Set-up Experimental
• 0,5-4 mg Pd/Membrane• AMS or COD in n-Heptane or Cumene
(CAMS= 1.4 mol/l; CCOD=0.4 mol/l)• 1 - 40 bar• T= 40-50 °C• VGemisch= 110 ml• Flow rate = 60-500 ml/min
MIC
FIC
TI
TI
PI
PI
T °
T °
H2
GC
PIC